Landscaping
Mulch Calculator
Enter your bed's length, width and depth to find how many cubic yards and bags of mulch you need.
How to use the mulch calculator
Measure your garden bed's length and width in feet, then choose how deep you want the mulch in inches. A 2–3 inch layer is right for most flower beds, while 3–4 inches gives better weed suppression and moisture retention. Type the numbers above and the mulch calculator shows cubic yards plus the number of standard bags you'll need to buy.
How the math works
Mulch is sold by volume, so the calculation is length × width × depth, with depth converted from inches to feet by dividing by 12:
- Cubic feet = length × width × (depth ÷ 12)
- Cubic yards = cubic feet ÷ 27 (bulk mulch is usually priced per cubic yard)
- 2 cu ft bags = cubic feet ÷ 2, rounded up to the next whole bag
- 3 cu ft bags = cubic feet ÷ 3, rounded up to the next whole bag
Worked example. For a 10 ft × 10 ft bed at 3 inches deep: cubic feet = 10 × 10 × (3 ÷ 12) = 25 ft³. That's about 0.93 cubic yards, which is 13 of the standard 2 cu ft bags or 9 of the larger 3 cu ft bags.
Mulch coverage reference
| Area (ft) | Depth | Cubic yards | 2 cu ft bags |
|---|---|---|---|
| 10 × 10 | 2 in | 0.62 | 9 |
| 10 × 10 | 3 in | 0.93 | 13 |
| 20 × 10 | 3 in | 1.85 | 25 |
| 20 × 20 | 3 in | 3.70 | 50 |
| 30 × 12 | 4 in | 4.44 | 60 |
Buying bulk by the cubic yard is usually cheaper for large areas, while bags are convenient for small beds. Order slightly more than the exact figure to allow for settling and uneven ground.
Frequently asked questions
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals about 14 of the standard 2 cu ft bags or 9 of the larger 3 cu ft bags. The calculator rounds bag counts up to whole bags.
How deep should mulch be?
Use 2–3 inches for flower beds and around shrubs, and 3–4 inches where you want stronger weed suppression and moisture retention. Avoid piling mulch against plant stems or trunks.
How do I calculate cubic yards of mulch?
Multiply length × width × depth (depth in feet), then divide by 27. For a 10 × 10 ft bed at 3 inches deep that's about 0.93 cubic yards. Enter your own measurements above.
Should I buy mulch in bags or in bulk?
Bags suit small beds and easy handling, while bulk delivery by the cubic yard is usually cheaper once you need more than around 8–10 bags. The calculator shows both so you can compare.
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